[jwarren]

It won't override global scope, it's just a hint the layout engine that your container's paint and/or size won't change, and thus it can optimise it's performance.

Wholly agree with your second point, it's something I see from a lot of junior devs. They just reach straight for flex/grid, and tbh I don't blame them. They are more predictable layout algorithms that are largely unshackled from legacy layout decisions.